The role of serpentinization and magmatism in the formation of decoupling interfaces at magma-poor rifted margins

doi:10.1016/j.earscirev.2019.102882

Earth-Science Reviews

Volume 196, September 2019, 102882

https://doi.org/10.1016/j.earscirev.2019.102882 Get rights and content

Abstract

In spite of recent progress in the understanding of magma-poor rifted margins, the processes leading to the formation and evolution of the exhumed mantle domain and its transition toward steady state oceanic crust remain debated. In particular, the parameters controlling the progressive localization of extensional deformation and magmatic processes leading to the formation of an oceanic spreading center are poorly understood. In this paper, we highlight the occurrence of two major decoupling horizons controlling the structural and magmatic evolution of distal magma-poor rifted margins. They are marked by strong seismic reflectors located at about 1 s TWTT (Upper Reflectors–UR) and 2 s TWTT (Lower Reflectors–LR) below top basement in domains of exhumed mantle at several magma-poor rifted margins. Both reflection seismic observations and studies on the physical properties of serpentinized mantle suggest that the UR likely results from deformation localized along a rheological interface at about 3 km below top basement, associated with an abrupt change in the mechanical behavior of peridotites once they are serpentinized to ~15%. We suggest that this interface played a major role in successive fault re-organizations during formation of the exhumed mantle domain. The comparison of reflection seismic observations with Alpine field analogues suggests that the LR likely results from an interaction between magmatism, deformation and hydration reactions during final rifting. Based on our results, we suggest that during final rifting the strain distribution is controlled first by hydration and then by magmatic processes in the domain of exhumed mantle.

Section snippets

Introduction and scientific context

Major progress has been made in understanding the architecture of magma-poor rifted margins (e.g., Peron-Pinvidic et al., 2013; Reston, 2009). At present, it is generally accepted that the transition zone located between the edge of continental and first unambiguous oceanic crusts, also referred to as the Ocean Continent Transition (OCT), can include a zone of exhumed subcontinental serpentinized mantle. The presence of such a basement type is attested at several distal rifted margins based on

Seismic observations: intra-basement reflections

In this section, we identify and characterize potential decoupling interfaces at Ocean Continent Transitions of magma-poor rifted margins. The studied areas are thus located between the edge of unambiguous continental and first oceanic crusts (Fig. 2). In this study we do neither investigate continental nor oceanic Mohos, nor the S-type reflections (localized landward of the continental crust termination) (Fig. 2). Except for the Iberia-Newfoundland rifted margins and the Tyrrhenian Sea where

Nature and origin of intra-mantle basement interfaces: constraints from geological observations and quantitative analyses

Our observations suggest that the UR and LR can be interpreted as distinct rooting levels for normal faults, and thus correspond to different decoupling interfaces (décollement levels). However, their nature and origin remain unclear from seismic observations only. Several hypotheses are possible to explain these décollements, such as (1) detachment/exhumation fault planes, (2) shear zones, (3) brittle-ductile transitions, (4) serpentinization fronts, (5) top of intrusive magmatic bodies (e.g.,

Serpentinization and accommodation of extensional deformation

Seismic and field studies show the presence of two major distinct decoupling levels in the basement of ultra-distal domains at magma-poor rifted margins. These decoupling levels are at different depths and appear to be associated with different processes. In the upper part of the lithosphere, extension is manifested by mantle exhumation along detachment faults. The serpentinization process occurring along these active exhumation faults leads to the formation of a major rheological interface at

Conclusions

Based on seismic observations, we highlighted the presence of two main intra-basement decoupling interfaces in the exhumed mantle domain at magma-poor rifted margins. Integrating physical properties of serpentinized rocks and constraints from Alpine field analogues allowed us to interpret and discuss the nature and origin of these interfaces. In particular, our results show the presence of a strong rheological interface at about 3 km below top basement. We suggest that this interface played a

Declaration of Competing Interest

None.

Acknowledgement

Seismic lines of the Antarctic surveys GA228 and GA229 were provided by Geoscience Australia after personal request and are published with the permission of Geoscience Australia. We also would like to thank I. Thinon and Ifremer for providing us the Norgasis 23 reflection seismic profile presented in this work. We kindly acknowledge Ekeabino Momoh for discussion and for the seismic image of the SWIR. This research was financed by Exxon Mobil as part of the CEIBA II project. We greatly thank

References (115)

D. Aslanian
Brazilian and African passive margins of the central segment of the South Atlantic Ocean
Kinematic constraints: Tectonophysics
(2009)
J.L. Bodinier
Geochemistry and petrogenesis of the Lanzo peridotite body, western Alps
Tectonophysics
(1988)
G. Boillot et al.
Ocean-continent boundary off the Iberian margin: a serpentinite diapir west of the Galicia Bank
Earth Planet. Sci. Lett.
(1980)
E. Bonatti et al.
Serpentinization of oceanic peridotites: temperature dependence of mineralogy and boron content
Earth Planet. Sci. Lett.
(1984)
J.W. Bown et al.
Variation with spreading rate of oceanic crustal thickness and geochemistry
Earth Planet. Sci. Lett.
(1994)
M. Gillard et al.
Fault systems at hyper-extended rifted margins and embryonic oceanic crust: Structural style, evolution and relation to magma
Mar. Pet. Geol.
(2016)
K. Higgie et al.
Deformation in a partially molten mantle: constraints from plagioclase lherzolites from Lanzo, western Alps
Tectonophysics
(2014)
G. Lymer et al.
3D development of detachment faulting during continental breakup
Earth Planet. Sci. Lett.
(2019)
G. Manatschal et al.
The Chenaillet Ophiolite in the French/Italian Alps: an ancient analogue for an Oceanic Core Complex?
Lithos
(2011)
C. Mével
Serpentinization of abyssal peridotites at mid-ocean ridges
Compt. Rendus Geosci.
(2003)

C. Mevel et al.

Amphibolite facies conditions in the oceanic crust: example of amphibolitized flaser-gabbro and amphibolites from the Chenaillet ophiolite massif (Hautes Alpes, France)

Earth Planet. Sci. Lett.

(1978)

T.A. Minshull

Geophysical characterisation of the ocean–continent transition at magma-poor rifted margins

Compt. Rendus Geosci.

(2009)

O. Müntener et al.

Refertilization of mantle peridotite in embryonic ocean basins: trace element and Nd isotopic evidence and implications for crust–mantle relationships

Earth Planet. Sci. Lett.

(2004)

A. Nicolas et al.

Interpretation cinematique des deformations plastiques dans le massif de Lherzolite de lanzo (Alpes piemontaises) — comparaison avec d’autres Massifs

Tectonophysics

(1972)

M. Nirrengarten et al.

Application of the critical Coulomb wedge theory to hyper-extended, magma-poor rifted margins

Earth Planet. Sci. Lett.

(2016)

G. Peron-Pinvidic et al.

Architecture of the distal and outer domains of the Mid-Norwegian rifted margin: insights from the Rån-Gjallar ridges system

Mar. Pet. Geol.

(2016)

G. Peron-Pinvidic et al.

Structural comparison of archetypal Atlantic rifted margins: A review of observations and concepts

Mar. Pet. Geol.

(2013)

S. Picazo et al.

Mapping the nature of mantle domains in Western and Central Europe based on clinopyroxene and spinel chemistry: Evidence for mantle modification during an extensional cycle

Lithos

(2016)

T.J. Reston

The structure, evolution and symmetry of the magma-poor rifted margins of the North and Central Atlantic: a synthesis

Tectonophysics

(2009)

C.N. Schuba et al.

A low-angle detachment fault revealed: Three-dimensional images of the S-reflector fault zone along the Galicia passive margin

Earth Planet. Sci. Lett.

(2018)

D.W. Sparks et al.

The generation and migration of partial melt beneath oceanic spreading centers

P. Agrinier et al.

Oxygen-isotope constraints on serpentinization processes in ultramafic rocks from the Mid-Atlantic Ridge (23°N)

M. Andreani et al.

Dynamic control on serpentine crystallization in veins: constraints on hydration processes in oceanic peridotites

Geochem. Geophys. Geosyst.

(2007)

F. Avedik et al.

Norgasis Cruise

(1994)

P. Ball et al.

The spatial and temporal evolution of strain during the separation of Australia and Antarctica

Geochem. Geophys. Geosyst.

(2013)

G. Bayrakci

Fault-controlled hydration of the upper mantle during continental rifting

Nat. Geosci.

(2016)

M.O. Beslier

Une large transition continent-océan en pied de marge sud-ouest australienne: premiers résultats de la campagne MARGAU/MD110

Bulletin de la société Géologique de France

(2004)

G. Boillot et al.

Non-volcanic rifted margins, continental break-up and the onset of sea-floor spreading: some outstanding questions

Geol. Soc. Lond., Spec. Publ.

(2001)

G. Boillot et al.

Rifting of the Galicia margin: crustal thinning and emplacement of mantle rocks on the seefloor

Proc. Ocean Drill. Progr, Sci. Results

(1988)

E. Bonatti et al.

Peridotites drilled from the Tyrrhenian sea, ODP Leg 107

W.R. Buck

flexural rotation of normal faults

Tectonics

(1988)

J.P. Canales et al.

Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

Geology

(2017)

D. Chian et al.

Crustal structure of the Labrador Sea conjugate margin and implications for the formation of nonvolcanic continental margins

J. Geophys. Res. Solid Earth

(1995)

D. Chian et al.

Deep structure of the ocean-continent transition in the southern Iberia Abyssal Plain from seismic refraction profiles: Ocean Drilling Program (Legs 149 and 173) transect

J. Geophys. Res. Solid Earth

(1999)

P.B. Cole et al.

Azimuthal seismic anisotropy in a zone of exhumed continental mantle, West Iberia margin

Geophys. J. Int.

(2002)

L. Cowie et al.

The palaeo-bathymetry of base Aptian salt deposition on the northern Angolan rifted margin: constraints from flexural back-stripping and reverse post-break-up thermal subsidence modelling

Pet. Geosci.

(2015)

S.M. Dean et al.

Deep structure of the ocean-continent transition in the southern Iberia Abyssal Plain from seismic refraction profiles: the IAM-9 transect at 40°20′N

J. Geophys. Res. Solid Earth

(2000)

S. Decitre et al.

Behavior of Li and its isotopes during serpentinization of oceanic peridotites

Geochem. Geophys. Geosyst.

(2002)

B.J. deMartin et al.

Kinematics and geometry of active detachment faulting beneath the Trans-Atlantic Geotraverse (TAG) hydrothermal field on the Mid-Atlantic Ridge

Geology

(2007)

L. Desmurs et al.

The Steinmann Trinity revisited: mantle exhumation and magmatism along an ocean-continent transition: the Platta nappe, eastern Switzerland

Geol. Soc. Lond., Spec. Publ.

(2001)

L. Desmurs et al.

Onset of magmatic accretion within a magma-poor rifted margin: a case study from the Platta ocean-continent transition, eastern Switzerland

Contrib. Mineral. Petrol.

(2002)

N.G. Direen et al.

Dominant symmetry of a conjugate southern Australian and East Antarctic magma-poor rifted margin segment

Geochem. Geophys. Geosyst.

(2011)

R.A. Dunn et al.

Three-dimensional seismic structure of the Mid-Atlantic ridge: an investigation of tectonic, magmatic, and hydrothermal processes in the Rainbow Area: Mid-Atlantic Ridge seismic structure

J. Geophys. Res. Solid Earth

(2017)

J. Escartín et al.

Nondilatant brittle deformation of serpentinites: implications for Mohr-Coulomb theory and the strength of faults

J. Geophys. Res. Solid Earth

(1997)

J. Escartín et al.

Strength of slightly serpentinized peridotites: Implications for the tectonics of oceanic lithosphere

Geology

(2001)

P. Fumagalli et al.

Experimental calibration of Forsterite–Anorthite–Ca-Tschermak–Enstatite (FACE) geobarometer for mantle peridotites

Contrib. Mineral. Petrol.

(2017)

T. Funck et al.

Crustal structure of the ocean-continent transition at Flemish Cap: Seismic refraction results

J. Geophys. Res.

(2003)

C. Gaina et al.

Breakup and early seafloor spreading between India and Antarctica

Geophys. J. Int.

(2007)

A.D. Gibbons et al.

The breakup of East Gondwana: assimilating constraints from Cretaceous ocean basins around India into a best-fit tectonic model

J. Geophys. Res. Solid Earth

(2013)

M. Gillard et al.

Tectonomagmatic evolution of the final stages of rifting along the deep conjugate Australian-Antarctic magma-poor rifted margins: Constraints from seismic observations

Tectonics

(2015)

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¹: Present address: Sorbonne Université, CNRS-INSU, Institut des Sciences de la Terre Paris, ISTeP UMR 7193, F-75005 Paris, France.

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The role of serpentinization and magmatism in the formation of decoupling interfaces at magma-poor rifted margins

Abstract

Section snippets

Introduction and scientific context

Seismic observations: intra-basement reflections

Nature and origin of intra-mantle basement interfaces: constraints from geological observations and quantitative analyses

Serpentinization and accommodation of extensional deformation

Conclusions

Declaration of Competing Interest

Acknowledgement

Kinematic constraints: Tectonophysics

Tectonophysics

Earth Planet. Sci. Lett.

Earth Planet. Sci. Lett.

Earth Planet. Sci. Lett.

Mar. Pet. Geol.

Tectonophysics

Earth Planet. Sci. Lett.

Lithos

Compt. Rendus Geosci.

Earth Planet. Sci. Lett.

Compt. Rendus Geosci.

Earth Planet. Sci. Lett.

Tectonophysics

Earth Planet. Sci. Lett.

Mar. Pet. Geol.

Mar. Pet. Geol.

Lithos

Tectonophysics

Earth Planet. Sci. Lett.

Oxygen-isotope constraints on serpentinization processes in ultramafic rocks from the Mid-Atlantic Ridge (23°N)

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Proc. Ocean Drill. Progr, Sci. Results

Peridotites drilled from the Tyrrhenian sea, ODP Leg 107

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The palaeo-bathymetry of base Aptian salt deposition on the northern Angolan rifted margin: constraints from flexural back-stripping and reverse post-break-up thermal subsidence modelling

Pet. Geosci.

Deep structure of the ocean-continent transition in the southern Iberia Abyssal Plain from seismic refraction profiles: the IAM-9 transect at 40°20′N

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Behavior of Li and its isotopes during serpentinization of oceanic peridotites

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Onset of magmatic accretion within a magma-poor rifted margin: a case study from the Platta ocean-continent transition, eastern Switzerland

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Geochem. Geophys. Geosyst.

Three-dimensional seismic structure of the Mid-Atlantic ridge: an investigation of tectonic, magmatic, and hydrothermal processes in the Rainbow Area: Mid-Atlantic Ridge seismic structure

J. Geophys. Res. Solid Earth

Nondilatant brittle deformation of serpentinites: implications for Mohr-Coulomb theory and the strength of faults

J. Geophys. Res. Solid Earth

Strength of slightly serpentinized peridotites: Implications for the tectonics of oceanic lithosphere

Geology

Experimental calibration of Forsterite–Anorthite–Ca-Tschermak–Enstatite (FACE) geobarometer for mantle peridotites

Contrib. Mineral. Petrol.

Crustal structure of the ocean-continent transition at Flemish Cap: Seismic refraction results

J. Geophys. Res.

Breakup and early seafloor spreading between India and Antarctica